1. Field of the Invention
The invention relates to the field of ultrasonic imaging, and in particular to ultrasonic imaging heads with rotating transducers.
2. Prior Art
In recent years, more emphasis has been placed on the use of ultrasonics to provide anatomical images of soft body tissue. This emphasis, to some extent, resulted from a public awareness of the dangers of x-rays, and also from the technical advances made in electronics. In the latter category, currently available integrated circuit memories, microprocessors, etc., have made possible the processing of signals which would not have been attempted a decade ago.
Numerous ultrasound scanners are commercially available which include a scanning head which is brought in contact with the human body. One or more ultrasound transducers transmit pulses of ultrasound and then sense the echoes which are displayed or recorded. High quality images are obtained, particularly where relatively large imaging heads are used. In many applications, however, smaller imaging heads are required to scan certain tissue. For example, a smaller imaging head or apparatus is required to view under the ribs for gall bladder images or to examine thyroid tissue.
One apparatus currently employed for scanning these more difficult regions includes a plurality of transducers which are rotated about a common axis where each transducer sequentially scans the body. A problem associated with this device (caused by reverberations) is described in conjunction with FIG. 1. A typical transducer with this configuration is described in U.S. Pat. No. 4,149,419.
As will be seen, the present invention provides an imaging head employing a plurality of transducers arranged in an off-axis configuration. This configuration eliminates the reverberation problems found in prior art devices.